464 J. B. WOODWORTH — VERTEBRATE FOOTPRINTS, PLAINVILLE 



sand and dust over the area of deposition. The shales at Plain ville offer 

 an opportunity for an investigation of the circumstances under which 

 they were made, and I rind nothing to support the idea that the cover 

 was not deposited in the same manner as the foundation on which these 

 prints were made. In both cases the rock is consolidated mud. That 

 the footprints may have been made beneath a slight depth of water seems 

 highly probable for the reason that some parts of the tracked surfaces 

 are marked with scratches (see plate 40, figure 2) such as would be 

 made by the toes or nails of a small newt in lightly touching the bottom 

 in swimming. If such light impressions can be preserved under water, 

 of course the stronger imprints of the foot may not only be made, but 

 preserved. 



